As is well known, many of today's laptop, notebook, desktop and other computers, as well as computer peripherals and other electronic products, are designed to receive removable devices such as cards conforming to the PC Card Standard established by the Personal Computer Memory Card International Association (PCMCIA), 2635 N. First Street, Suite 209, San Jose, Calif. 95131 (U.S.A.). The PC Card Standard, including the latest release (March 1997), is incorporated herein by reference in its entirety. The PC Card Standard defines the electrical and physical specifications of the PC Card including the interfaces between the card and the port or slot into which the card is inserted. The specifications include a 16-bit PC Card interface and a 32-bit CardBus PC Card interface. The Standard also enables 3.3 and 5 volt operation. A physical keying mechanism for 3.3 volt cards protects them from being damaged in a 5 volt host system slot. The PCMCIA standard also specifies three card form factors, called Type I, Type II and Type III. All three card types measure the same length (85.6 mm) and the same width (54.0 mm), and differ only in overall thickness. Thus, the Type I card has a thickness of 3.3 mm; the Type II card, 5.0 mm; and the Type III card, 10.5 mm. PC cards may be used for various purposes. For example, Type I cards are typically used for memory devices; Type II cards are typically used for I/O devices, as will be described below; and Type III cards have been typically used to house rotating mass storage devices (disk drives). Presently, Type II cards are used principally as communication links, for example, for connecting the user of a host system such as a portable computer to an Ethernet LAN, as a data/fax modem for connecting the user to a subscriber telephone line system, or as a combined LAN and modem card. In one popular arrangement an adapter cable is used to couple the relatively thin Type II card to the much larger, standard RJ-11 or RJ-45 receptacle of a telephone line or Ethernet network. A drawback of this arrangement is that besides the computer, one or more bulky adapter cables must be carried by the user in order to connect the computer to a LAN or telephone line system thereby defeating at least to some extent the advantages afforded by portable computers. In addition, these adapter cables are often lost. Another disadvantage of adapter cables is that the connection between the thin card and the cable is fragile and subject to electrical contact interruption and consequent loss of data transfer.
One solution to the problem of incompatibility between the PC Type II standard communications card and the RJ-type connector is to add to the rear end of the Type II card an enlarged housing enclosing a receptacle sized and configured to receive an RJ-type connector plug. The incorporation of such an RJ receptacle housing allows the 5 mm Type II communications card to interface directly with a LAN or telephone system using an existing LAN or telephone cable with an RJ-11 or RJ-45 modular plug at each end. However, although this approach eliminates the need for a separate adapter cable assembly, the housing on the end of the card for receiving the RJ-type connector projects from the host system enclosure often requiring the removal of the card when transporting a portable computer in an attache case or the like.
Another approach to the elimination of the need for external adapter cables is a communications card that allows an RJ-type modular plug to be inserted directly into an aperture formed in a retractable access portion of a Type II communications card. Such an approach is disclosed, for example, in U.S. Pat. No. 5,183,404 issued Feb. 2, 1993. Yet another approach to eliminating the need for adapter cables is disclosed in U.S. Pat. No. 5,773,332 issued Jun. 30, 1998 and incorporated herein by reference. FIG. 21 of U.S. Pat. No. 5,773,332 shows a Type III card incorporating in the rear thereof a pair of RJ-xx series receptacles (specifically an RJ-11 receptacle and an RJ-45 receptacle) for directly connecting the card to a LAN network and/or telephone line.
The typical host system card slot has a height conforming to the Type III standard (10.5 mm) that can accommodate two stacked Type II PC cards each 5.0 mm thick, or a single Type III card. The slot includes longitudinally extending upper and lower channel pairs, each pair adapted to receive the longitudinal side rails of one of the cards. As is known, each card has a conventional 68-contact connector at one end that is adapted to mate with a corresponding 68-pin connector along the rear wall of the host system slot when the card is fully inserted in the slot. A slot that can accommodate two Type II cards will therefore have a pair of stacked 68-pin connectors, that is, an upper and a lower host connector, one for each card connector. A key, dimensioned and configured in accordance with the PC Card Standard, is provided along the front end of each of the longitudinal sides of the card to prevent the card from being completely inserted in the slot upside down and to protect a 3.3 volt card from being plugged into and thereby damaged by a 5 volt slot.
One of the advantages of Type III communication cards of the kind disclosed in the aforementioned patents and application is that the rear receptacles on such cards can directly receive standard modular plugs such as the RJ-11 and RJ-45 plugs on existing cables, thereby eliminating the need for adapters (also known as "dongles"). However, each such card is provided with a specific receptacle or combination of receptacles thereby requiring the purchase of a new card in order to upgrade and/or add a new communication function. The purchase of an additional card either makes the first card redundant or the use of the cards inconvenient since the original card and the new card cannot be used in the same slot simultaneously.
It would therefore be desirable to provide for greater flexibility in the combination of communication card functions available to the user at a reasonable cost.